Optical Engineering

Instant Photogrammetry With a Grid The term photogrammetry is usually associated with photography from the air, but in the strict sense of the word, it refers to any photographic technique in which measurements are made. Properly calibrated, even the simplest of cameras is capable of making measurements to respectable accuracies. In those cases where the accuracy requirements are not too excessive, instant-developing films offer the advantage of providing data quickly and at the same time allowing the photogrammetrist the opportunity to check his results while still in the field. The technique to be described in this article is limited to measurements taken on level areas, namely inside buildings and on streets and other flat exterior grounds. It utilizes a transparent perspective grid, Figure I, that is superimposed with the resulting picture to indicate scale) The method has application in plant layout surveys, accident investigations, architectural studies, traffic surveys, etc.